Preparation of dyeable acrylonitrile polymer fibers using 4, 4&#39;-diaminostilbene-2, 2&#39;-disulfonic acid



United States Patent 3 380 798 PREPARATION or DYEABLE ACRYLONITRILE POLYMER FIBERS USING 4,4'-DIAMINOSTIL- BENE-2,2-DISULFONIC ACID Pompeiio A. Ucci, Pensacola, Fla, assignor to Monsanto Company, St. Louis, Mo., a corporation of Delaware No Drawing. Continuation-impart of application Ser. No. 238,781, Nov. 19, 1962. This application June 19, 1967, Ser. No. 647,242

6 Claims. (Cl. 8-100) ABSTRACT OF THE DISCLOSURE Acrylonitrile polymer fibers having improved basic dye acceptance are produced by contacting the acrylonitrile polymer fibers in the gel state with 4,4-diaminostilbene- 2,2.'-disulfonic acid or an alkali metal salt thereof.

CROSS REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of my copending application, Ser. No. 238,781, filed Nov. 19, 1962, entitled, Method for Improving Dyeing Characteristics, now abandoned.

BACKGROUND OF THE INVENTION (1) Field of the invention This invention relates to the preparation of acrylic fibers having improved basic dye acceptance.

(2) Description of the prior art Acrylic polymer compositions, particularly fiber-forming compositions, possess a number of characteristics which render them of substantial value for a variety of textile and other purposes. However, it is also well known that such compositions are difiicult to dye with basic dyes due to the hydrophobic nature of the acrylic fibers, filaments and other shaped articles. A large number of basic dyes have been developed with good fastness properties. This has rendered of prime importance attempts to im prove the basic dyeability of acrylic polymer compositions. Various means have been developed to bring about this improvement. Acrylonitrile monomers have been polymerized with small amounts of a copolymerizable monomer such as an unsaturated sulfonate. Blends of acrylic polymers wih polymers having basic dyeability have been attempted. The use of pressure-dyeing techniques at temperatures above the atmospheric boiling point of a polymeric mixture, low temperature dyeing processes and various special dyeing assistants have also partly alleviated this problem but are too limited in scope to be generally useful. A simple means of increasing basic dye acceptance of acrylic polymers is highly desirable. Such means should enable satisfactory level dyeing to the desired shades using conventional dyes and methods. It should produce a modified fiber that is susceptible to all types of basic dyes without otherwise changing the desired physical characteristics.

SUMMARY OF THE INVENTION The present invention provides acrylonitrile polymer fibers and filaments having improved dyeability with basic dyes and is accomplished by contacting the acrylonitrile polymer fiber while still in the gel state with 4,4'-diaminostilbene-2,2'-disulfonic acid or an alkali metal salt thereof such as the sodium or potassium salt.

The additives of this invention are preferably used in a treatment bath in the form of an aqueous solution containing from about 0.1 to 10 percent of the additives based on the weight of the solution.

3,380,798. Patented Apr. 30, 1968 It has been found that the additives of this invention may be added to solution spun acrylonitrile polymer fibers and filaments after extrusion, and while the fibers are still in the gel state. The use of the term gel state refers to the condition of the fiber after extrusion and during coagulation, washing and orientation of the molecules by stretching and before the fiber is collapsed by drying to its final density andarea ratio. During this gel state the fiber has a bulk density of .4 to .6 gm./cc., measured on a freeze dried sample. After collapsing, the fiber has a density of from about 1.16 to 1.19 gm./ cc. which is roughly equivalent to the density of the polymer prior to extrusion. Since the additives employed in thepractice of this invention contain no polymerizable components, they cannot act as copolymerizable monomers. Furthermore, they cannot be satisfactorily applied as an additive after the fiber is collapsed and dried since subsequent scouring and other textile processing operations will remove most of the additive which is deposited on the surface rather than throughout the fiber. But, if the additive is added to the fiber in the gel state, preferably by means of a separate treatment bath, it is occluded into the fiber, forming anionic dye sites in situ, and also keeping other dye sites which may be present in the fiber open and receptive to dyes. Thus, these additives may be referred to as an anionic gel state additive. The fiber may then be collapsed, dried and subjected to further processing without the loss of the additive.

The amount of additive which may be employed in the practice of this invention will of course vary with the concentration of the additive in solution and with the spinning conditions. In general, the additives are used in the form of an aqueous solution containing from about 0.1 to 10 percent of the additive and preferably 0.5 to 5 percent of the additive, based on the weight of the solution. It has been determined that approximately to percent of this additive will be absorbed by the gel fiber as it passes through the treatment bath. This means that the fiber in its final form after collapsing and any further treatments that may be used will contain from about 0.05 to 5.0 percent of the additive, based on the weight of the fiber.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The acrylic polymers of this invention include polyacrylonitrile and copolymers, terpoiymers, interpolymers and blends of acrylonitrile with other polymerizable monoolefinic materials, as well as blends of polyacrylonitrile and such polymerized mono-olefinic materials with small amounts of other polymeric materials, such as styrene. In general, a polymer made from a monomer mixture of which acrylonitrile is at least percent by weight of the polymerizable content or a blend of polymers containing at least 70 percent of polymerized acrylonitrile is useful in the practice of the invention. Block and graft copolymers of the same general type are within the purview of the invention.

For example, the polymer may be a copolymer of from to 98 percent acrylonitrile and from 2 to 20 percent of another monomer containing the C=C linkage and copolymerizable with acrylonitrile. Suitable mono-olefinic monomers include acrylic, alpha-chloroacrylic and methacrylic acids; the methacrylates such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, methoxymethyl methacrylate, beta-chloroethyl methacrylate, and the corresponding esters of acrylic and alpha-chloroacrylic acids; vinyl chloride, vinyl fluoride, vinyl bromide, vinylidene chloride, l-chloro-l-bromoethylene; methacrylonitrile; acrylamide and methacrylamide, alphachloroacrylamide or monoalkyl substitution products thereof; methyl vinyl ketone; vinyl carboxylates such as vinyl acetate, vinyl chloroacetate, vinyl propionate and N-vinylsucc'mimide; methylene malonic esters; itaconic esters; N-vinylcarbazole; vinyl furane; alkyl vinyl ethers; vinyl sulfonic acid; ethylene alpha-beta-dicarboxylic acids or their anhydrides or derivatives such as diethyl fumarate, diethyl maleate, diethyl citraconate, diethyl mesaconate; styrene; vinyl naphthalene; acenaphthalene; vinyl-substituted tertiary heterocyclic amines, such as the vinylpyridines, for example, 2-vinylpyridine, 4-vinylpyridine, 5- methyl-2-vinylpyridine, etc., l-vinylimidazole and alkylsubstituted-l-vinylimidazoles, such as 2-, 4, or S-methyl-lvinvlimidazole, and other C=C containing copolymerizable materials.

The polymer may be a ternary interpolymer, for example, products obtained by the interpolymerization of acrylonitrile and two or more of any of the monomers enumerated above. More specific-ally, a useful ternary polymer comprises acrylonitrile, methacrylonitrile, and 2-vinylpyridine. The ternary polymers may contain for example, from 80 to 97 percent of acrylonitrile, from 1 to percent of a vinylpyridine or a l-vinylim'idazole, and from -1 to d8 percent of another substance, such as methacrylonitnile or vinyl chloride.

The polymer may also be a blend of from 50 to 98 percent of polyacrylon-itrile or of a polymer containing from 80 to 99 percent acrylonitrile and from 1 to percent of at least one other C=C containing substance copolymerizable with acrylonitrile, with from 2 to 50 percent of a blending polymer, of from 10 to 70 percent of acrylonitrile and from to 90 percent of at least one other C=C containing polymerizable monomer. Preferably, when the polymeric material comprises a blend, it will be a blend of (1) a copolymer of 90 to 98 percent of acrylonitrile and from 2 to 10 percent of another m'ono-ole'fin'ic monomer such 'as vinyl acetate, with (2) a sufii'cient amount of a copolyrner of from 10 to 70 percent of acrylonitrile and 'from 30 to 90 percent of a vinyl-substituted tertiary heterocyclic amine, such as vinylpyridine, methyl vinylpyridine or l-vinylimidazole, the two blending polymers being so as to give a dyeable blend having an overall vinyl-substituted tertiary heterocyclic amine content of from 2 to 10 percent based on the weight of the blend. Other blend compositions such as blends of polyvinyl chloride or polyvinyl-idene chloride with the above described blend, the overall blending composition containing at least 70 percent polymerized acrylonitrile, are also with the purview of the invention.

The polymers useful in the practice of the present invention may be prepared by any conventional polymerization procedure, such as mass polymerization methods, solution polymerization methods, or aqueous emulsion procedures. The preferred practice utilizes suspension polymerization wherein the polymer is prepared in finely divided form for immediate use in the fiber fabrication operations. The preferred suspension polymerization may utilize batch procedures wherein monomers are charged with an aqueous medium containing the necessary catalyst and dispersing agents. A more desirable method involves the semi-continuous procedure in which the polymerization reactor containing the aqueous medium is charged with the desired monomers gradually throughout the course of the reaction. Entirely continuous methods involving the gradual addition of monomers and the continuous withdrawal of polymer may also be employed.

The most eflFective polymers for the preparation of fibers are those of uniform physical and chemical prop- V employed in the manufacture of fibers and filaments from acrylonitrile polymers. The present invention is applicable to the usual methods for forming synthetic filaments and fibers, such as dry spinning and wet spinning. Any of the Well known prior art solvents, coagulation baths and orientation and washing methods normally used in solution spinning may be used in the practice of the invention. Heat and light stabilizers, delu'sterants, plasticizers and other like modifying agents may be. incorporated with the polymeric compositions disclosed herein Without departing from the scope of the invention and without detrimental effects from these gel state additives. Antistatic agents, lubricants and other additives which are either anionic or nonionic may be applied to the fiber in the gel state along with the additives of this invention.

The process and composition of this invention are of distinct advantage over the prior art. There is no need to use inconvenient pressure dyeing conditions to achieve commercially acceptable dyeing properties. The involved step of the incorporation of dye receptive materials in the polymer during its preparation is eliminated. Basic dye acceptance of the modified acrylonitrile polymer fibers of the invention is at a sufficiently high level to make possible dyeing in deep shades with basic dyes. Color, heat stability, dye penetration and washfastness are also improved. Numerous other advantages of the present invention will be apparent to those skilled in the art.

The following example is presented as a further disclosure and illustration of the improved products of this invention and is not intended as a limitation thereof. All parts, proportions and percentages are by weight unless otherwise indicated.

EXAMPLE Fiber Was prepared from a dope composed of approximately 94 percent acrylonitrile and 6 percent vinyl acetate and a conventional solvent by extrusion into a conventional coagulating bath composed of water and solvent. This fiber was stretched, washed, and before drying, passed through a conventional finish bath containing 0.5 percent of 4,4-diaminostilbene-2,2'-disulfonic acid. The fibers were then dried and scoured in a conventional manner and subjected to a conventional dyeing process using a conventional basic blue dye. The fibers were dyed a strong blue and dye penetration of the fibers was uniformly good.

It is seen that by the use of the additives of this invention, acrylonitrile polymer fibers produced by a conventional spinning method showed a marked improvement in their basic dye uptake. This is true concerning both the scoured fibers and the unscoured fibers when they have been treated with the special additives of this invention while still in the gel state. This will aid greatly in permitting the use of these acrylonitrile polymer fibers in manufacturing yarns of natural color or yarns which will be dyed with very dark shades of color.

It is understood that changes and variations may be made in the present invention by one skilled in the art without departing from the spirit and scope thereof as defined in the appended claims.

I claim:

1. A composition of matter comprising an acrylonitrile polymer fiber and from about 0.05 to 5.0 percent by weight of 4,4'-diaminostilbene-2,2'-disulfonic acid or an alkali metal salt thereof.

2. The composition of claim 1 wherein the additive is present in amounts of from about 0.25 to 2.5 percent by weight.

3. The composition of claim 2 wherein the acrylonitrile polymer fiber consists of a copolymer of at least percent by weight acrylonitrile and up to 20 percent by weight of a copolymerizable mono-olefinic monomer.

4. A process for the preparation of dyeable acryloni- 5 trile polymer fibers comprising contacting the fiber in the gel state with a solution comprising from about 0.1 to 10.0 percent, based on the weight of the solution, of 4,4'-diaminostilbene-2;2'-disulfonic acid or an alkali metal salt thereof.

5. A proces as defined in claim 4 wherein the additive is present in the solution in amounts of from about 0.5 to 5.0 percent, based on the weight of the solution.

'6. A process as defined in claim 4 wherein the acrylonitrile polymer fiber consists of a copolymer of at least 80 percent by weight acrylonitrile and up to 20 percent by weight of a copolymerizable mono-olefinic monomer.

6 References Cited UNITED STATES PATENTS 2,457,838 1/ 1949 Sitzler et al. 85O 5 2,468,431 4/ 1949 lE'berhart et al 81.1 2,819,943 1/1958 Rhyner et a1. 8-55 FOREIGN PATENTS 1,028,867 5/ 1966 Great Britain.

10 NORMAN G. TORCHIN, Primary Examiner.

T. I. HERBERT, JR., Assistant Examiner. 

